Many processes have been developed for producing hydrocarbons from various hydrocarbonaceous materials such as oil shale and tar sands. Historically, the dominant research and commercial processes include above-ground retorts and in-situ processes. More recently, encapsulated impoundments have been developed for recovering oil from crushed oil shale (In-Capsule® technology). These impoundments are formed primarily of earthen materials, with the crushed oil shale being encapsulated by an impermeable barrier made of rock, soil, clay, and geosynthetics, among other materials. The encapsulated impoundments can be very large, sometimes occupying several acres.
Generally, methods for recovering hydrocarbon products from oil shale involve applying heat to the oil shale. Heating oil shale allows kerogen in the oil shale to break down through the process of pyrolysis, yielding liquid and vapor hydrocarbon compounds. One issue in these processes is the loss of heat to surroundings. This “fugitive heat” has negative effects on the process because the heat lost is not useful for accomplishing the process objective of producing hydrocarbon products. Excessive fugitive heat can also heat the surrounding environment to temperatures that are unacceptable. One method of addressing this problem in above-ground retorts is installing insulation to maintain heat inside the retort. For in-situ processes such as the Shell Oil in-situ process, a freeze wall can be formed by using a refrigerant to cool edges of a production zone below the freezing temperature of water. These solutions can be costly and energy-intense. Accordingly, research continues to find efficient methods of recovering hydrocarbon products while minimizing fugitive heat.